The Cooperative Study of Sickle Cell Disease (CSSCD) is a multi-institutional, cooperative investigation conducted by the Sickle Cell Disease Branch, Division of Blood Diseases and Resources, National Heart, Lung, and Blood Institute. Thirty-nine hundred (3900) patients have been enrolled and are presently followed at twenty-three clinical sites (fifteen contracts). This contractor is responsible for coordinating and managing the comprehensive, detailed, and integrated database for this investigation. The overall management includes maintaining confidential data files, monitoring completion of study objectives and center performance, generating reports, providing data analysis, and participating in the publishing of the results.